Air guiding element, especially an air guiding channel for a motor vehicle

ABSTRACT

An air conduction element ( 1 ), particularly an air conduction channel for a motor vehicle, having a reverberant channel body ( 2 ) manufactured from plastic, which has at least one wall region replaced by a sound-absorbing component ( 10, 11 ), the sound-absorbing component having an at least partially exposed outer side. An edge region of the sound-absorbing component ( 10, 11 ) be extrusion-coated with the plastic of the channel body ( 2 ) in such a way that the sound-absorbing component ( 10, 11 ) is connected in a form-fitting way to the channel body ( 2 ) along at least a section of its circumference.

CROSS REFERENCE TO RELATED APPLICATIONS

Applicants claim priority under 35 U.S.C. §119 of German Application No.102 61 081.9 filed on Dec. 20, 2002. Applicants also claim priorityunder 35 U.S.C. §365 of PCT/EP03/011947 filed on Oct. 28, 2003. Theinternational application under PCT article 21(2) was not published inEnglish.

The present invention relates to an air conduction element, particularlyan air conduction channel for a motor vehicle, having a reverberantchannel body manufactured from plastic, which has at least one wallregion replaced by a sound-absorbing component, the sound-absorbingcomponent having an at least partially exposed outer side.

An air conduction element of this type is known from DE 91 00 514 U1.The known air conduction element includes a channel body which ismanufactured as an injection molded part from reverberant plastic, e.g.,polypropylene. A window-like opening is left open in the wall of thedimensionally stable channel body. This opening is covered with aninsulating part, which has both a sound insulating and a sound dampingeffect. The insulating part is made of melamine resin foam, which isinternally and externally enclosed by a textile nonwoven. The support ofthe insulating part on the channel body is implemented in such a waythat a lower edge of the insulating part is inserted into a clampsupport and at least an upper edge of the insulating part is riveted,clipped, or screwed to the channel body. The edge and the clamp supportare implemented like a tongue and groove receiver, the insulating partbeing held clamped along the lower edge via an insertion strip on thechannel body. Clips, screw connections, or rivets may also be providedon the lateral edge regions and/or edges of the insulating part.Manufacturing this air conduction element is relatively time-consumingand costly, particularly because of the clamp support, which includesthe insertion strip.

Furthermore, air conduction elements according to the species, in whichthe sound-absorbing component is glued to the edge of the window-likeopening or recess of the channel body using an adhesive, are known. Airconduction elements of this type are described, for example, in Japanesepatent applications JP 6156052 and JP 6156054. In order to ensure areliable adhesive bond, it is typically necessary to subject theadhesive areas to a suitable surface treatment beforehand. If thechannel body is made of polypropylene and the sound-absorbing componentis made of polyethylene terephthalate, for example, a plasma treatmentof the adhesive areas is typically performed beforehand in order toensure reliable adhesion of the pieces to the channel body and thesound-absorbing component. These air conduction elements are alsorelatively costly to manufacture because of the use of adhesive and thepossibly necessary surface treatment of the adhesive areas.

The object of the present invention is to modify an air conductionelement of the type cited at the beginning in such a way that it may bemanufactured more cost-effectively with the same or even improvedacoustic effect.

This object is essentially achieved according to the present inventionin that an edge region of the sound-absorbing component isextrusion-coated with the plastic of the channel body in such a way thatthe sound-absorbing component is connected to the channel body in aform-fitting way along at least part of its circumference. Thesound-absorbing component is therefore held in the channel body like aframe.

The air conduction element according to the present invention requiresthe use of neither an insertion strip nor clips, screw connections, orrivets, nor the use of adhesive, nor a surface treatment in the form ofa plasma treatment for the support of the sound-absorbing component. Themanufacture of the air conduction element according to the presentinvention therefore requires fewer work steps than typical airconduction elements according to the species. In addition, themanufacture of air conduction elements according to the presentinvention may be automated more easily than is the case for theabove-mentioned known air conduction elements. The present inventiontherefore allows a significantly more rapid, controlled, andcost-effective manufacture of air conduction elements according to thespecies.

In particular, now even relatively small and complexly shaped openingsof air conduction elements according to the species may be provided withsound-absorbing wall sections cost-effectively.

An advantageous embodiment of the air conduction element according tothe present invention is distinguished in that the sound-absorbingcomponent is connected to the channel body in a form-fitting way alongits entire circumference. In this way, a peripheral seal may be achievedon the edge of the sound-absorbing component. If unacceptably high airand/or pressure losses arise at the sound-absorbing component because ofits construction from an air-permeable absorber layer, this may beavoided according to a further embodiment of the present invention, ifnecessary, by providing the sound-absorbing component on the outsidewith a film which is impermeable to air or with a microperforated filmwhich is largely impermeable to air.

A further preferred embodiment of the present invention is that thechannel body of the air conduction element is implemented as a one-piecehollow body. This means that the channel body is not assembled frommultiple parts, such as from two halves, but rather is manufactured as aone-piece hollow body in the injection molding method. In this way, thework steps in the manufacture of the air conduction element are reducedfurther. It is obvious, however, that it is also possible to assemblethe channel body from multiple parts, particularly from two halves.

The sound-absorbing component may preferably have an air-permeable layermade of polyethylene terephthalate (PET). This layer may additionally becoated on one or both sides with a nonwoven. In principle, however, thesound-absorbing component may be made not only from PET, but rather alsofrom other suitable sound-absorbing materials and/or compositematerials.

Both the channel body and the sound-absorbing component and possibly afilm positioned on the outer side of the sound-absorbing component maybe made of polyethylene terephthalate (PET). In this way, type-purerecycling of the air conduction element is made possible and/or easier.

Further preferred and advantageous embodiments of the present inventionare specified in the subclaims.

In the following, the present invention will be described in greaterdetail on the basis of a drawing, which illustrates multiple exemplaryembodiments.

FIG. 1 shows a top view of an air conduction element in the form of aventilation channel which has multiple branches;

FIG. 2 shows a bottom view of the air conduction element shown in FIG.1; and

FIG. 3 shows a sectional view of the air conduction element shown inFIG. 1, in section along the line A—A.

The air conduction element 1 illustrated in the drawing is intended forinstallation in a motor vehicle. The air conduction element 1 includes areverberant channel body 2, manufactured from plastic, which is usedhere for air distribution to multiple air outlet nozzles (not shown). Inthe installed state, air is supplied via the connection opening 3 anddistributed to the air outlet nozzles via the branch openings 4, 5, 6,7, 8, and 9.

Ventilation noises, which are frequently found to be disturbing by thevehicle occupants, arise during the generation of an air flow by aventilator in the motor vehicle and during the conduction and/orredirection of the air flow. Engine noises may also be transmitted intothe inside of the vehicle via the air conduction system, which isproduced from channels and/or hoses.

In order to damp and/or reduce such ventilation and engine noises, atleast one wall region of the reverberant channel body 2 is replaced by asound-absorbing component 10, 11, and/or 12. In the exemplary embodimentshown, a wall region on the outer curve is replaced over the curvelength B by a sound-absorbing component 10. In addition, two furthersound-absorbing components 11 and 12 may be positioned on the wallregion of the channel body 2 on the inner curve, near the branchopenings 4 to 9 (cf. FIGS. 2 and 3).

The channel body 2 is an injection molded part which is manufacturedfrom polypropylene, polyethylene terephthalate (PET) or another suitablethermoplastic in the “one-shot method”. The channel body 2 is preferablyimplemented as a one-piece injection molded part. However, embodimentsof the channel body which may be produced more advantageously frommultiple parts are also possible. In such cases, the parts and/or halvesmay be connected to one another by welding and/or heat sealing orthrough clamps, clips, or the like.

The sound-absorbing components 10, 11, 12 are inserted as anacoustically active material into an injection molding tool (not shown).This may preferably be performed automatically using a robot or thelike. The injection molding tool (injection mold) is implemented in sucha way that the sound-absorbing components 10, 11, 12 are each extrusioncoated on their edge in such a way that the particular sound-absorbingcomponent is connected to the channel body 2 in a form-fitting way alongat least a section of its circumference. However, an embodiment in whichthe particular sound-absorbing component 10, 11, and/or 12 is connectedin a form-fitting way to the channel body 2 along its entirecircumference is preferred.

The sound-absorbing component 10, 11, and/or 12 is largely exposed bothon its inner side and on its outer side. Only its edge isextrusion-coated. The channel body 2 thus forms a kind of frame for theparticular sound-absorbing component 10, 11, and/or 12. In order toachieve this, a special tool technology is necessary, in which thesound-absorbing components 10, 11, 12 are clamped between two or moretool parts in such a way that the thermoplastic injection moldingcompound extrusion coats the edge of the particular sound-absorbingcomponent, but does not cover the inner side and outer side of thesound-absorbing component. Thus, a window-like opening arises in thechannel body 2, which is closed by the sound-absorbing component 10, 11,and/or 12. As may be seen in FIG. 3, the edge of the particularsound-absorbing component is therefore held in a peripheral grooveand/or enclosed by peripheral webs 13, 14.

The sound-absorbing components 10, 11, 12 themselves may be made ofdifferent sound-absorbing materials. For example, a porous,air-permeable foam layer and/or nonwoven layer may be used. Inparticular, a preferred embodiment is to use an air-permeable layer 15made of polyethylene terephthalate for the sound-absorbing component 10,11, and/or 12.

Furthermore, sandwich structures are also advantageous. Thus, in theexemplary embodiment shown here, the air-permeable layer 15 of thesound-absorbing component is provided with a carrier nonwoven 16 and acover nonwoven 17.

The external nonwoven 17 may additionally be covered with a film whichis impermeable to air to prevent possible air losses via thesound-absorbing component. In FIG. 3, the sound-absorbing component 11includes an air-permeable layer 15, which is laminated internally with anonwoven 16 and externally with a film 18 which is impermeable to air.

Under certain circumstances, it may also be advantageous if amicroperforated film (not shown) is positioned on the outer side of theair-permeable layer 15 or on the outer side of the nonwoven 17.

The sound-absorbing component 10 positioned in the wall region of thechannel body 2 on the outer curve may be subjected to a shaping processbeforehand, so that it is tailored optimally to the curve and/or shapeof the channel body 2. However, it is also possible to use slab-shapedabsorber material which is first shaped corresponding to the contour ofthe channel body 2 during the injection molding process.

The present invention is not restricted to the exemplary embodimentsdescribed above and illustrated in the drawing. Rather, an array ofvariations are conceivable, which make use of the ideas according to thepresent invention defined in the claims even if they have asignificantly differing design. Thus, for example, it is also possibleto implement the sound-absorbing component 10 with a varying thickness,particularly as wedge-shaped. It is also in the scope of the presentinvention to use sound-absorbing components 10, 11, 12 having a texturedinner side, such as a wavy inner side or one having protrusions.

1. An air conduction element (1), for a motor vehicle, having areverberant channel body (2) manufactured from plastic, which has atleast one wall region replaced by a sound-absorbing component (10, 11,12), the sound-absorbing component having an at least partially exposedouter side, wherein an edge region of the sound-absorbing component (10,11, 12) is extrusion-coated with the plastic of the channel body (2) insuch a way that the sound-absorbing component (10, 11, 12) is connectedin a form-fitting way to the channel body (2) along at least a sectionof its circumference.
 2. The air conduction element according to claim1, wherein the sound-absorbing component (10, 11, 12) is connected in aform-fitting way to the channel body (2) along its entire circumference.3. The air conduction element according to claim 1, wherein thesound-absorbing component (10, 11, 12) is produced from a porous,air-permeable layer (15) made of sound-absorbing material.
 4. The airconduction element according to claim 1, wherein the sound-absorbingcomponent (10, 11, 12) is produced from an air-permeable layer (15) madeof polyethylene terephthalate.
 5. The air conduction element accordingto claim 3, wherein the air-permeable layer (15) of the sound-absorbingcomponent is provided with a carrying nonwoven (16) and a coveringnonwoven (17).
 6. The air conduction element according to claim 1,wherein the sound-absorbing component (11) is provided on the outsidewith a film (18) which is impermeable to air.
 7. The air conductionelement according to claim 1, wherein the sound-absorbing component (10,11, 12) is provided on the outside with a microperforated film.
 8. Theair conduction element according to claim 1, wherein the sound-absorbingcomponent (10) is implemented as a curved molded part.
 9. The airconduction element according to claim 1, wherein the channel body (2) isimplemented as a one-piece hollow body.
 10. The air conduction elementaccording to claim 1, wherein the channel body (2) and thesound-absorbing component (10, 11, 12) are each produced frompolyethylene terephthalate.
 11. The air conduction element according toclaim 1, wherein the channel body (2), the sound absorbing component(10, 11, 12) and a film (18) positioned on the outside of thesound-absorbing component are each produced from polyethyleneterephthalate.
 12. The air conduction element according to claim 3,wherein the air-permeable layer (15) of the sound-absorbing component isprovided with a carrying nonwoven (16) or a covering nonwoven (17).